The demand of beyond 4th Generation (4G) mobile communications includes not only high transmission rate but also the capability to provide QoS guaranteed services to high user density areas under the constraint of limited radio spectrum. Cognitive radio is considered as a core technology for future wireless communications in which the wireless spectrum can be dynamically shared between primary mobile network operators and secondary networks. Femtocell is a new mobile technology proposed for providing wireless voice and broadband services to customers in small areas such as the home, office or designated locations. In the paper, we present a cognitive femtocell-cellular network model which we consider as a mobile network model used for beyond 4G mobile communications. We will discuss selected channel allocation schemes and compare their performance obtained by computer simulation.